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MCAT
Course: MCAT > Unit 11
Lesson 1: Biological basis of behavior: Nervous system- Biological basis of behavior: endocrine system questions
- Structure of the nervous system
- Functions of the nervous system
- Motor unit
- Peripheral somatosensation
- Muscle stretch reflex
- Autonomic nervous system
- Gray and white matter
- Upper motor neurons
- Somatosensory tracts
- Overview of the functions of the cerebral cortex
- Hemispheric differences and hemispheric dominance
- The old brain
- Cerebellum
- Brainstem
- Subcortical cerebrum
- Cerebral cortex
- Neurotransmitter anatomy
- Early methods of studying the brain
- Lesion studies and experimental ablation
- Modern ways of studying the brain
- Endocrine system and influence on behavior - Part 1
- Endocrine system and influence on behavior - Part 2
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Hemispheric differences and hemispheric dominance
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- Most left-handed individuals are still left-brain dominant- this was relevant in a question on one of my practice exams actually. Only like 5% of lefties have a different dominant hemisphere- what was stated in the video atabout lefties having right brain dominance is mostly incorrect. 2:24(20 votes)
- The way this is explained makes it sounds like the Broca's area and Wernicke's area are on the dominant side of the brain only, and that they are on different sides for people with different dominant sides.(13 votes)
- In most people, regardless of which side of their brain is dominant, aren't language areas on the left side of the brain? I was taught that it is very rare to have Wernicke's and Broca's areas on the left and the same areas on the right side of the brain usually control non-verbal communication.(6 votes)
- Atwhen smell is mentioned what is ipsilateral? and did it mean smell also is controlled by both hemispheres? 1:40(2 votes)
- I think this means that whenever a smell is detected, it is controlled by the hemisphere from the same side. That is, no crossing of the axons to the other side when the information is been sent to the brain. I guess an example will be that if a smell is detected by a receptor in the right nostril, it will be processed by the right hemisphere and vice- versa.(6 votes)
- In the beginning of the video, it was mentioned that the left side of the brain is responsible for the right side's movements, vice versa. It was also mentioned that we have dominant sides of our brain in physical movements. If so, if for example, I was left brain dominant, than would my sight be better on the right side, my hearing, and my footwork as well?(1 vote)
- No, that is not quite how it works. It is possible to be left handed and right legged, or the opposite, and there is no guarantee that even if you are both right legged and right handed your right eye or ear has better sight/hearing than the other side. Besides the different sightedness tests do not even agree if a person is "right eye dominant or left eye dominant" http://www.aaopt.org/ocular-dominance-comparison-tests. According to Wikipedia, if a person is myopic by a different amount on each eye, it is likely that the most myopic will in fact be the dominant one (according to the hole-in-card test, I assume).(2 votes)
- Is audition also ipsilateral?(1 vote)
- From my understanding, audition has afferent fibres going BILATERALLY to the brain...so damage on one side of the brain doesn't mean you will be deaf on either ear.
However, after doing some reading, I have read that only TASTE is ipsilateral (and touch, of course, is contralateral) From what I read, audition and olfaction have a bit of both going on...
Can anyone else confirm/disconfirm any of this?(1 vote)
Video transcript
- [Voiceover] Here I have something that looks like a picture
of two different brains, but I actually want you to
think about it as two halves of the same brain. So imagine, if you
will, that I drew a line down the center of someone's head, and then split their
brain down the middle. In both cases, this side would
be the front of the brain, and this would be the back, and this would be the top, and here would be the bottom. And let's say that this
person was looking at you when we peeled their brain in two. In that case, this would be
their left side of their brain, and this would be their right side. The first thing you might
notice, looking at this brain, is that the sides are basically identical. And that is absolutely correct. For the most part, the two sides look physically
identical to one another. But even though they look identical, for a great majority of people,
the two sides of the brain actually do different things. And we're gonna talk a
little bit about that. The first thing that I wanna talk about is contralateral control. And what that means, for the most part, is that the left side of the brain controls the right side of the body, and vice versa. So the right side of the brain controls the left side of the body. And this is true for
basically all of your senses. So information from your left visual field goes to the right side
of your occipital cortex, the motor neurons on the
right side of your brain control the left side of your body. The only thing that I
can immediately think of that this doesn't apply to is smell. So in that case, the
two cerebral hemispheres communicate with the
same side of the body. In other words, they
communicate ipsilaterally instead of contralaterally. Another interesting thing to note is that we actually have
a dominant hemisphere. Meaning that we also
have a nondominant one. And because we know that
the brain communicates contralaterally with the body, the dominant hemisphere
is typically the one that's opposite of the
hand that we write with. So people who are right-handed have a tendency to be left-brained, and vice versa. But because being
right-handed is so dominant, this means that the left hemisphere is the dominant hemisphere for
the vast majority of people. Although handedness is the easiest way to identify our dominant hemisphere, the dominant hemisphere
is actually responsible for a lot more than that. One thing that we find in
the dominant hemisphere, which is typically the left hemisphere, is language. Specifically, an area called Broca's area, which is responsible
for speech production, and Wernicke's area, which is
responsible for comprehension, are both located in the
dominant hemisphere. There's also been some research that shows that the dominant hemisphere
is analytic in nature. That along with language, things
like logic and math skills are also both mainly controlled
by the dominant hemisphere. The nondominant hemisphere,
typically the right hemisphere, has a less prominent role in language, but it is responsible
for many other tasks. For example, the nondominant hemisphere plays an important role in understanding the emotional tone of language. And it allows us to recognize whether the people that we're speaking to are happy or depressed or anxious, just by the way that they sound. So while the nondominant
hemisphere may not control language in the way that the
dominant hemisphere does, it still plays an important role. Research has also implicated that the non dominant hemisphere
may play an important role in things like creativity, and music, and spatial processing. There's also been some evidence that shows that the nondominant hemisphere helps us pull together
big-picture concepts. I do want to take a moment to note, before we go any further, that it's really easy to get carried away with this left brain, right brain thing. I've seen a lot of things
on the internet that say, "Hey, take this quiz and it'll show you "if you're left-brained or right-brained," and it doesn't really work like that. The vast majority of
people have a dominant and a nondominant hemisphere, and we use both of them. There's not really a way to
tap in to one over the other, so you need to be really careful in how you interpret this information. One last thing you
might be wondering about is that if we have two
different cerebral hemispheres, how do they talk to one another? How do they communicate? And the answer is that they communicate through a large band of fibers, known as the corpus callosum. And without this corpus callosum, the two sides of the
brain can't communicate with one another. Each one doesn't know what
the other one is doing. And that can produce some incredibly interesting consequences that we're going to talk
about in a future video.